Bounce Attack
From Sonic Retro
The Bounce Attack, also known as the Bound Jump, was first introduced in Sonic Adventure 2, and also appears in Sonic Advance 2 and Sonic the Hedgehog (2006 game). When Sonic presses the action button (usually or ) during a jump, he will crash down before bouncing back up. In the 3D games, Bounce Attacks can be strung together to reach high areas.
Sonic Advance 2 is the only game where the Bounce Attack is a default ability. In other games, players must find or purchase a "Level-Up" item to use the move.
Bugs
In Sonic Adventure 2, by spindashing toward a wall, jumping if necessary, and pressing at the moment of arrival at the wall, the bounce attack will actually trigger off the wall instead of the floor, and with the momentum of the spindash to boot. This can allow Sonic to reach exorbitant heights, up to seven times as high as a standard bounce can provide.